Sulfonylaminoethyl α-substituted acrylates are promising compounds as monomers for next-generation photoresist materials, and resists containing the monomers as constituent elements are known to be excellent in light transparency and surface adsorptivity (see, for example, U.S. Pat. No. 6,165,678, which is hereinafter referred to as “Patent Document 1”).
In Patent Document 1, there is no detailed description concerning the synthesis of the fluorine-containing alkylsulfonylaminoethyl α-substituted acrylate represented by the above-shown general formula [3] which is an objective compound of the invention, and the document merely discloses that sulfonylaminoethyl α-substituted acrylates in a broad sense can be synthesized by condensation of the corresponding sulfonylaminoethanol with α-substituted acryloyl chloride.
The process of Patent Document 1 mentioned above is a general process for manufacturing an α-substituted acrylic ester but there is no description therein concerning the synthesis of sulfonylaminoethyl α-substituted acrylates wherein R2 is a fluorine-containing alkyl group such as a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a perfluoroethyl group, an n-perfluoropropyl group, or an n-perfluorobutyl group.
According to the process of Patent Document 1, it can be presumed that the fluorine-containing alkylsulfonylaminoethyl α-substituted acrylate represented by the above-shown general formula [3] which is an object of the invention may be produced by reacting an α-substituted acryloyl chloride represented by general formula [4]:
wherein the meaning of R1 is the same as that defined above,with a fluorine-containing alkylsulfonylamino ethanol represented by general formula [5]:
wherein the meaning of R2 is the same as that defined above. At first, it was considered that the fluorine-containing alkylsulfonylamino ethanol represented by general formula [5] could be synthesized by reacting (through sulfonamidation reaction) aminoethanol represented by the formula [6a]:
or a salt of aminoethanol represented by the formula [6b]:
wherein Xn− is a counter anion (such as a fluoride ion, a chloride ion, a bromide ion, an iodide ion, a perchlorate ion, a perbromate, a hydrogen sulfate ion, or a sulfate ion) and n is a positive integer,with a fluorine-containing alkylsulfonyl halide represented by general formula [2a]:
or a fluorine-containing alkylsulfonic anhydride represented by general formula [2b]:
wherein, in the formulae [2a] and [2b], the meaning of R2 is the same as that defined above, and Y is a fluorine atom, a chlorine atom or a bromine atom.
However, the studies made by the present inventors revealed that in the case of a substrate wherein R2 is a fluorine-containing alkyl group, which is a target of the invention, the sulfonamidation does not satisfactorily proceed and the formation of the fluorine-containing alkylsulfonylaminoethanol is not ascertained. Specifically, even when reaction temperature and time sufficient for promoting the reaction are applied, the presence of the fluorine-containing alkylsulfonylaminoethanol in the reaction mixture was not confirmed by gas chromatography of the substrate excluding a solvent (see Comparative Example 1). The fact that the fluorine-containing alkylsulfonylaminoethanol is not obtained in a sufficient yield gives serious influences from economic and operational viewpoints on the production of the fluorine-containing alkylsulfonylaminoethyl α-substituted acrylate represented by general formula [3] which is a final objective compound of the invention.
Thus, it is difficult to efficiently synthesize the fluorine-containing alkylsulfonylaminoethyl α-substituted acrylates based on the conventional technology and hence it is a problem to find out a process for producing the same in more reliable manner.